I knew one who was Polish, and he pronounced it the Polish way.
But I can't understand
Lukasz on an American child unless he is of Polish descent. It looks weird and ignorant. I also hate it when non-Turkish people use the name
Aydin as a variant of
Aidan. The two names are not even related.
I know my name,
Erik, is a Scandinavian spelling, while
Eric is the usual English spelling, but
Erik seems to be considered English by now.